The present invention relates to an indwelling needle assembly including an indwelling needle to be temporarily indwelt in a blood vessel for infusion or the like. More specifically, the present invention relates to an indwelling needle assembly where, after an inner needle and an outer needle are simultaneous pierced into tissue of a living body, and the outer needle is retained in the tissue and the inner needle is removed from the outer needle, the inner needle can be safely and readily stored in a needle guard.
An indwelling needle used for infusion or the like ordinarily has a double-needle structure composed of an outer needle and an inner needle. Upon its use, the indwelling needle is pierced into a blood vessel in a state where the inner needle is positioned in a lumen of the outer needle. After the outer needle is inserted to a predetermined position, the inner needle is removed from the lumen of the outer needle and an infusion line or the like is connected to a proximal end portion of the outer needle so that an infusion, a liquid medicament or the like is introduced into the blood vessel through the lumen of the outer needle. The outer needle is made of a flexible resin that is unlikely to damage the inside of the blood vessel. The inner needle is generally made of a metal that is easy to insert into the blood vessel.
After the outer needle of the indwelling needle is retained in a body of a patient, the inner needle that is removed from the lumen of the outer needle is disposed of. On this occasion, medical personnel, patients or other persons may be injured by touching the sharp tip of the inner needle. If the tip of the inner needle is protected by a suitable method, the inner needle itself used for a patient suffering from a disease that infects through blood, such as hepatitis or acquired immune deficiency syndrome (AIDS), can be an infection medium, not to speak of the tip itself of the inner needle.
For this reason, it is very important to properly dispose of the inner needle that has been used to pierce a blood vessel of a patient. However, priority is given to treatment of a patient and disposal of inner needles is frequently postponed.
In recent years, indwelling needle assemblies for immediate and easy disposal of inner needles after use (Japanese Patent Application Laid-open Nos. Hei 3-63066, Hei 6-78999, Hei 6-86821, Hei 7-328116, Hei 11-57002, etc.) have been proposed.
These indwelling needle assemblies are composed of a tubular housing having arranged therein an inner needle hub connected to an inner needle and a needle guard slidably arranged between the housing and the inner needle hub and having a catheter connected to a distal end thereof. After removing the inner needle from a lumen of an outer needle of the indwelling needle assembly while retaining the outer needle in a patient, the needle guard is slid toward the distal end of the housing so that the inner needle can be easily accommodated in the needle guard. Since, after removing the inner needle, the inner needle can be easily protected by one hand of a person, these indwelling needle assemblies free the person of the fear that the person will be hurt by the tip of the inner needle or infected with diseases by blood adhered to the inner needle.
However, in each of these indwelling needle assemblies, the needle guard, which is longer than the inner needle, is slid toward the distal end of the housing by the length of the inner needle. Therefore, it is difficult for medical personnel with small hands to completely protect the inner needle by sliding the needle guard using one hand. Further, in the case of medical personnel other than those with small hands, when using a long indwelling needle such as one retained in a femoral vein of the inguinal region at the time of emergency dialysis, it is difficult to slide the needle guard using one hand to a position where the inner needle can be completely protected. Japanese Patent Application Laid-open No. Hei 7-328116 discloses a piercing needle whose needle casing for accommodating an inner needle has a telescopic structure comprising several short tubes. When the indwelling needle is retained in the human body, it is easy for medical personnel with small hands to use it since it has a small size. However, it is still necessary to slide the needle casing toward the distal end of the housing by the length of the inner needle to protect the inner needle removed from the indwelling needle.
On the other hand, taking the above problems in consideration, an indwelling needle assembly has been developed in which a spring is arranged between an inner needle hub and a proximal end portion of a needle guard. When a locking mechanism of a push button type in the indwelling needle assembly is released, the inner needle hub is moved toward the proximal end of the needle guard by the force of the spring (Japanese Patent Application Laid-open Nos. Hei 8-215315 and Hei 9-103492).
However, in the case of indwelling needle assemblies with a push-button type locking mechanism, when a long indwelling needle such as the one described above is used, it takes a certain time for the inner needle to be accommodated in the needle guard. As a result, there is increased fear that medical personnel will be hurt by the tip of the inner needle or infected with diseases by blood adhered to the inner needle. On the other hand, when a strong spring is used to shorten the time necessary for accommodating the inner needle, the hand of a medical person holding the indwelling needle assembly receives a greater impact at the time of accommodating the inner needle and the indwelling needle assembly may be dropped or the medical personnel may feel anxiety because of the impact. Also, there is a fear that the impact may cause scattering of the blood that remains inside the inner needle.
Under the above circumstances, an object of the present invention is to provide an indwelling needle assembly in which an inner needle of the indwelling needle can be easily accommodated in a needle guard by one hand without receiving a strong impact which may cause medical personnel to feel uneasy if a long indwelling needle is used or if it is used by medical personnel with small hands, and that requires only a short time for accommodating the inner needle and is free of the fear of blood scattering.
With a view to solving the above-mentioned problems, the inventor of the present invention conducted extensive research. He found an indwelling needle assembly comprised of a needle guard having a multi-tube structure composed of a plurality of telescoping tubes, a first elastic body for extending the needle guard and, a second elastic body for drawing an inner needle hub into the needle guard. As a result, there is a shortened time for accommodating the inner needle in the needle guard in the indwelling needle assembly as compared with the time of a conventional indwelling needle assembly and a small impact is given to the hand that holds the indwelling needle assembly. The present invention has been achieved based on this discovery.
That is, the present invention provides an indwelling needle assembly characterized as comprising an outer needle to be pierced into and retained in a tissue of a living body, an outer needle hub having a distal end portion to which the outer needle is fixed, an inner needle slidably inserted in a lumen of the outer needle and having a sharp blade edge at a distal end portion thereof, an inner needle hub having a distal end portion to which the inner needle is fixed, a needle guard of a multi-tube structure which is composed of a plurality of telescoping tubes and is capable of accommodating the inner needle and the inner needle hub therein, a first elastic means provided on the needle guard for extending the plurality of telescoping tubes so as to extend, or lengthen, the needle guard, a second elastic means which engages the inner needle hub and is capable of biasing the inner needle hub toward a proximal end side of the needle guard, and a stopper means capable of holding the inner needle hub and the needle guard against the biasing forces of the first and second elastic means, respectively.